Ok it is half a year after the last post but to answer the original question:
Drive: Who uses it?
Why? Because I only have to motor
in and out of very small harbors where the boat
can't tag, the rest I sail, so for me using a diesel engine
just for about 5 min each time is very bad for the engine
I actually use the electric
drive a lot less than 5 min, just a burst to get out the slip, and one to turn before drifting out under the staysail. In total maybe 1 minute.
Motoring in takes still 5 minutes of use. (against the wind
, no room to tag)
The other problem here is that they use floating dock
lines on buoys for the "Mediterranean mooring
style" so the harbor is literally a spaghetti bowl of it.
With a diesel
and a cold gearbox
even in neutral the prop can still turn, on the electric it's not unless you go too fast ofcourse. So sometimes we slide over some lines with less chance to get caught.
But the main reason is the capability to regenerate during sailing.
I know that a lot of people are against the idea because they don't want to lose speed for a little bit of power but by calculating everything and optimizing the system to regenerate rather than being able to push the boat to hullspeed I was positively surprised with the results.
To push a boat it seems to be better to connect the motor
But to generate it is better to have a reduction so that for every prop turn your motor turns several turns.
like in a car with different gears could sound as a good solution but I think that the friction produced by it will be too great to be effective and I prefer a system without having to do oil
changes or the chance of an oil leak
and having to have cans with oil
onboard as before.
So I made a pulley reduction of 1/3 what seems to work
well to generate and have still enough speed to push up the headwind in the harbor, it actually gives more torque on the propshaft so my next propeller
will be a 4 blade to make the system more efficient at lower revs.
Until now we were unable to measure a significant speed difference while sailing freewheeling or charging
, there has to be a difference for sure but on my boat not noticable. I think this is because my electric motor
is only a 7,5KW motor for a boat of 28t on paper it is not a lot at all to push it but still better than rowing ;-)